A network anomaly is an unusual event in a network that is of interest to an entity such as a network provider, a network user, a network operator, or a law enforcement agency. A network anomaly may be created unintentionally as a result of normal network traffic conditions, such as a breakdown in a network resource. A network anomaly may also be created intentionally by a malicious attack by a hacker or a person acting to damage the network or impair the performance of the network.
Typically, a network anomaly is monitored, or analyzed, by collecting data from a network element such a single link or a single router of the network. Such data collection is done in isolation from other network data or other network elements. In other words, finding a network anomaly is closely related to a link-level traffic characterization.
Another approach to monitor or analyze a network anomaly treats a network anomaly as a deviation in traffic volume. This enables detection of a network anomaly that visually stands out, but a low-rate network anomaly (e.g., worms, port-scans, small outage events, etc.) are not detected by an approach based on traffic volume.
Still another approach to monitor or analyze a network anomaly is a manual method where a rule is developed. A match or a violation of the rule decides whether a network anomaly has been encountered. However, rule-based methods cannot detect new, previously unseen anomalies.
Many current methods provide a solution, for an element of the network, for each class of a network anomaly, whereas a solution for many elements of a network is preferable.